The Animal Health Service (AHS) is one of the two components of the Research Animal Resources Center (RARC). RARC maintains an accredited animal care and use program supporting the research activities at MSKCC. The principal goal of the AHS is to maintain and improve the health status of the experimental animals at the Center. All animals are evaluated daily and any health problems are treated under guidance of the veterinary staff, thus providing MSKCC investigators with high quality research animals necessary for their studies. A species-specific health monitoring program continuously assesses the colony health of the resident animals detecting subclinical infections which could potentially interfere with ongoing research. Incoming animals are evaluated during a comprehensive quarantine program, which makes high quality, unique research models readily available to MSKCC investigators. These efforts are supported by the Research Animal Diagnostic Laboratory (RADL). The RADL also provides research support such hematology or pathology examinations to individual investigators. The AHS operates a surgical facility that is available to investigators, anesthesia and/or surgery support is provided on request. The AHS provides training to investigators in basic animal research techniques through lectures and wet labs and offers more specific training as requested. Technical assistance is available for a wide variety of procedures. A more recent addition is a compliance section, which continuously reviews the animal research activities at the Center to assure compliance with applicable federal and state regulations, allowing the research at the Center to progress unimpeded. Future development of the service includes quantitative growth parallel to the expected increase in animal numbers but also qualitative growth by refining the services provided to investigators. Two examples are research services such as tumor monitoring provided at the new satellite facility in Long Island City and the establishment of a Phenotyping Core that will provide comprehensive characterization of genetically engineered animals.